Offset issues, such as DC offset in receivers is a known concern that must be dealt with in order for a receiver to operate properly on current systems employing suitable modulation. DC offset may be viewed as a DC error term that ends up added to and as part of a received signal. These error terms can result from various sources, such as a difference between a transmitted frequency and a frequency that the receiver is tuned to. The error terms may also result from various mismatches within a receiver lineup, e.g., mismatches in quadrature mixers or other mismatches in other circuitry such as amplifiers and the like. These mismatches may be more pronounced in receiver lineups that are implemented substantially in integrated circuit form since techniques, such as suitable blocking capacitors, are not readily available to mitigate the DC error terms.
It can also be important to rapidly and accurately determine and correct for these DC offsets in order to minimize signal acquisition times and the like. In many situations, such as relatively low symbol rate modulation, conventional techniques for determining DC offset do not allow for a rapid and accurate determination of DC offset. Conventional techniques generally include evaluating statistical properties, such as an average of the signal. In order to get an accurate estimate these properties may be evaluated over 10s or 100s of symbols. When the symbol duration is long, i.e., symbol rate is low, averaging for a sufficient period of time to insure accuracy does not provide a DC offset determination in the appropriate time frame.